Can Living with a Pregnant Person Impact Your Cycle?

I am 36 weeks pregnant, and my wife is noticing abnormalities with her cycle. Can my hormones be impacting it?

—Catherine K

We used to think that women who lived in close proximity to one another were likely to see the timing of their menstrual cycles shift to occur in sync. More recent data has debunked that myth, pointing to flaws in the initial data collected.

The hormones circulating in a woman’s blood during pregnancy are significantly higher than the levels seen during a normal menstrual cycle, though. Might those much higher levels of estrogen and progesterone cause changes to the menstrual cycles of other women living with the pregnant woman?

There is no evidence to suggest that your high hormone levels would have an effect on your wife’s menstrual cycle. However, I can imagine other factors that might be affecting it. There are a number of studies — many of them reviewed here — that show that stress disrupts menstrual regularity. The types of stress included are varied, from job stress to living amid war.

Recent illness, even a poorly timed cold, can also affect menstrual regularity, but these types of disruptions should be short-lived. If irregularities persist for more than a few months, she should see her doctor to look for possible causes.

The upshot: Many factors can cause menstrual irregularity, but there is no evidence that a partner’s pregnancy would do so. Any irregularities that persist for more than a few cycles should be evaluated with your doctor.